[GitHub] [pulsar-client-go] hunter2046 commented on pull request #507: Expose GetHashingFunction() method on producer

[GitBox <gi...@apache.org>]

hunter2046 commented on pull request #507:
URL: https://github.com/apache/pulsar-client-go/pull/507#issuecomment-822802546


   > The point is wrong, can MessageRouter not meet our functions?
   > 
   > e.g:
   > 
   > ```
   > 	producer, err := client.CreateProducer(ProducerOptions{
   > 		Topic: "my-partitioned-topic",
   > 		MessageRouter: func(msg *ProducerMessage, tm TopicMetadata) int {
   > 			fmt.Println("Routing message ", msg, " -- Partitions: ", tm.NumPartitions())
   > 			return 2
   > 		},
   > 	})
   > ```
   
   Thanks for taking a look. MessageRouter is what we need. We'd like to set the MessageRouter to a function that works similar to the defaultRouter with a customized number of partitions, e.g.
   
   ```
   	internalRouter := pulsarClient.NewDefaultRouter(
   		getHashingFunction(producerOptions.HashingScheme),
   		producerOptions.BatchingMaxMessages,
   		producerOptions.BatchingMaxSize,
   		producerOptions.BatchingMaxPublishDelay,
   		producerOptions.DisableBatching)
   	messageRouter := func(message *pulsarClient.ProducerMessage, metadata pulsarClient.TopicMetadata) int {
                    // customNumberOfPartitions could be different from metadata.NumPartitions() here
   		return internalRouter(message, customNumberOfPartitions)
   	}
   ```
   
   The problem is that `getHashingFunction` is not exposed so we can't use it to feed the `NewDefaultRouter` method.


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